Balance Systems for Sash Windows

How To Recognise Sash Window Balance Systems

How To: Identify Sash Window Balance Systems

Table of Contents

For a vertical sliding sash to stay in an opened position some form of counter-balance is required.  Let’s take a look at the options that have been developed.

Swivel Block

The earliest solution for keeping a sliding sash open.  Simply a physical stop that swivels into place, below the sash, to stop it from dropping.

Sash Pins / Sash Spring Bolts

sash pin - sash spring boltSpring loaded bolts that locate into holes drilled in the jamb, every six inches or so.  Windows with sash pins were the cheapest option and soon became known as ‘guillotine windows’.

 

Traditional Sash Weight And Cord

Sash weights on scales.A traditional box sash window uses a steel or lead weight, attached to a cord, passed over a pulley and fixed to the glazed sash frame.  As the window is operated the weights travel upwards or downwards concealed inside the frame.  

Any increase in weight, such as fitting thicker glass requires the weights to be re-balanced using small add-on weights known as ‘make weights’.  Make-weights are usually cast from Lead.

  • The original and still the best system -when correctly set-up.
  • The momentum of the weights allows the sash to glide.
  • Time proven, simple system.
Some early sash cords were made from hemp or jute but pre-stretched braided cotton cord became the standard.  The cord diameter required corresponds to the pulley wheels selected; Too large and the cord will foul the pulley, too small and the cord can become lodged between the wheel and the pulley body.

Spiral & Spring Balance

1948

Sash Window Spiral Balance.Invented in America these balances were introduced in the 1930’s, but their popularity really took off after the war. Spring balances offered a cheaper way to manufacture vertical sliding sash windows; not a better way. There are several variations of these balances but they all utilise a spring to offset the weight of the sash. The windows do not glide like a weighted sash; the spring simply stops the sash from dropping. Originally the spring was encased in a metal sheath but for many years now has come with a plastic one.

  • Available in a wide range of sizes to suit any window.
  • Time proven design

 

Tape Balance (ACME Balance, Pullman Coils)

New Window Tape BalanceAnother American invention that became popular after the war, also offered as a budget way to manufacture vertical sliding sash windows. Similar to an everyday retractable tape measure in design, the end of the tape connects to the bottom of the sash. As the window opens the tape retracts into the balance.

Larger frames require 1 pair of balances per sash (2 pairs = 4 balances per window) but on smaller windows it’s common to find only 1 balance and a guide wheel (2 balances & 2 guides per window).

This system was deleted for many years but has recently been reintroduced into the USA. Uncommon in the UK where the spring balance was far more popular, but used extensively in the USA & Australia.

Jamb Liners (Tilt & Slide)

Tilt and Slide Sash WindowsA variation of the spring balance. This system was designed to offer the extra functionality of tilting inwards for supposed easier cleaning. In practise very few people make use of this option and in our experience they are often a disappointing balance system.  Much of the weight is carried on flimsy plastic lugs that don’t last.

Other Balance Systems

Alternative systems come and go.  Most new balance systems incorporate a spring balance at their core.

The Sash Counter Balance Systems That Never Became Popular

Sash Balance Documentation

1939 : “Modern details by Unique for architects, contractors, millwork dealers.
by Unique Balance Co., Inc.”

Spring spiral balances for sash windows

1939 : Pullman ; unit sash balances.
by Pullman Mfg. Corp.

Pullman tape balances

191-? American sash chain
by American chain company inc.

c. 1930 : Grand rapids all-steel sash pulleys.
by Grand Rapids Hardware Co

1914 : Howarth reversible sash centers.
by Michigan Engine Valve Co.

1959 : Whitco Sash Hardware
by Vincent Whitney Company

1938 : Anderson complete window units.
by Anderson Corp

1915 : Catalogue of sash operating apparatus as manufactured by Lord & Burnham Co.
by Lord & Burnham Co.

Period Window Restoration